1. Field of the Invention
This invention relates to an information-signal recording apparatus and an information-signal reproducing apparatus. Also, this invention relates to an information-signal recording and reproducing apparatus. In addition, this invention relates to an information-signal communication apparatus. Furthermore, this invention relates to an information-signal recording medium.
2. Description of the Related Art
A typical optical-disc recorder/player operates as follows. During a recording mode of operation of the recorder/player, a signal representing at least one of video information and audio information is compressed into a compression-resultant information signal. An optical head in the recorder/player records the compression-resultant information signal on an optical disc. During a playback mode of operation of the recorder/player, the optical head reproduces a recorded signal from an optical disc. The reproduced signal is expanded into an original information signal.
It is known to provide such an optical-disc recorder/player with a buffer memory having a capacity of about 4 Mbits. A recorded signal is reproduced from an optical disc at a transfer rate of 10.08 Mbps. The reproduced signal is converted into an information signal having a variable transfer rate lower than 10.08 Mbps. The buffer memory absorbs the difference in transfer rate between the before-conversion signal and the after-conversion signal.
Japanese published unexamined patent application 10-92158 discloses a disc reproducing apparatus designed as follows. Discontinuation and disturbance of an image are prevented by dividing a cell into a plurality of cells, time-division-multiplexing the cells in each scene and arranging and recording the cells to be reproduced continuously within the distance of the particular amount of codes to shorten the physical moving distance during the reproducing operation. In Japanese application 10-92158, a video program has a preceding front trunk scene A, a plurality of branch scenes B0 to B3, and a successive rear trunk scene C. In the case of recording a plurality of branch scenes on a recording medium, any branch scene is arranged in such a manner that a scene cell appears in the same rate for the summed total scene length. Arrangement should be done so that when the time for jumping the distance for the amount of particular codes is defined as Ts, the relationship Tcxe2x88x92[Tcxc3x97Pr/Rr] greater than Ts can be set for the amount of readout data Rr, amount of codes consumed Pr and image reproducing time Tc. When arrangement for recording is performed, a physical moving distance during the reproducing operation can be shortened and generation of discontinuation and disturbance of image can be prevented. The branch scenes B0 to B3 are multiple scenes. Each of the branch scenes B0 to B3 has a sequence of cells. The cells of the branch scenes B0 to B3 are shuffled before being recorded on a disc (a recording medium). Thus, the recorded cells of the branch scenes B0 to B3 are on non-successive separate positions on the disc. Accordingly, during the reproduction of the sequence of cells of one branch scene, a pickup head reproduces the cells and repetitively jumps between non-successive separate positions on the disc. In the apparatus of Japanese application 10-92158 includes a buffer memory capable of absorbing a time interval during which a pickup head jumps between non-successive separate positions on the disc so that reproduced data continue to be absent. Japanese application 10-92158 indicates the relation between the capacity of the buffer memory and a seek time of the pickup head which enables the buffer memory to continuously output data under conditions where the pickup head reproduces a sequence of cells of one branch scene and repetitively jumps between non-successive separate positions on the disc.
Japanese published unexamined patent application 6-139696 discloses a recording and reproducing apparatus which includes a buffer memory for absorbing a difference between transfer rates. In Japanese application 6-139696, during a recording mode of operation of the apparatus, first digital data having a lower transfer rate and being derived from an information signal to be recorded is converted into second digital data with a higher transfer rate. The second digital data are recorded on a disc at the higher transfer rate. During a playback mode of operation of the apparatus, third digital data are reproduced from the disc at the higher transfer rate, and the reproduced digital data are converted into fourth digital data related to the lower transfer rate. The fourth digital signal is converted into a reproduced information signal. The recording mode of operation and the playback mode of operation are implemented on a time sharing basis so that the information signal to be recorded and the reproduced information signal can simultaneously occur.
It is a first object of this invention to provide an improved information-signal recording apparatus.
It is a second object of this invention to provide an improved information-signal reproducing apparatus.
It is a third object of this invention to provide an improved information-signal recording and reproducing apparatus.
It is a fourth object of this invention to provide an improved information-signal communication apparatus.
It is a fifth object of this invention to provide an improved information-signal recording medium.
A first aspect of this invention provides an apparatus for reproducing information from a recording medium having first and second areas on which first and second information signals are recorded respectively, the first information signal having a size Ya, the second information signal having a size Yb. The apparatus comprises a head for reproducing the first and second information signals from the first and second areas of the recording medium and transmitting the reproduced first and second information signals on a time sharing basis and at a predetermined constant transfer rate Rp while moving between the first and second areas of the recording medium; and a buffer memory for receiving the first and second information signals from the head at the predetermined constant transfer rate Rp, for temporarily storing the first and second information signals, and for outputting the first and second information signals at first and second transfer rates Ra and Rb respectively, the first and second transfer rates Ra and Rb being lower than the predetermined constant transfer rate Rp; wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the size Ya of the first information signal, the size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:
(Ya+Yb)xe2x89xa7Rpxc2x7(Ra+Rb)xc2x7(Tab+Tba)/(Rpxe2x88x92Raxe2x88x92Rb) 
A second aspect of this invention provides an apparatus for recording information on a recording medium having first and second areas. The apparatus comprises a buffer memory for receiving first and second information signals at first and second transfer rates Ra and Rb respectively, for temporarily storing the first and second information signals, and for outputting the first and second information signals at a predetermined constant transfer rate Rp higher than the first and second transfer rates Ra and Rb, the first information signal having a size Ya, the second information signal having a size Yb; and a head for receiving the first and second information signals from the buffer memory, and for recording the first and second information signals on the first and second areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving between the first and second areas of the recording medium; wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the size Ya of the first information signal, the size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:
(Ya+Yb)xe2x89xa7Rpxc2x7(Ra+Rb)xc2x7(Tab+Tba)/(Rpxe2x88x92Raxe2x88x92Rb) 
A third aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having first and second areas, the first area being loaded with a first information signal having a size Ya. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate Rp; and a buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate Ra lower than the predetermined constant transfer rate Rp; the buffer memory being for receiving a second information signal at a second transfer rate Rb lower than the predetermined constant transfer rate Rp, for temporarily storing the second information signal, and for outputting the second information signal at the predetermined constant transfer rate Rp, the second information signal having a size Yb; the head being for receiving the second information signal from the buffer memory, and for recording the second information signal on the second area of the recording medium at the predetermined constant transfer rate Rp; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the second information signal on the second area of the recording medium on a time sharing basis while moving between the first and second areas of the recording medium; and wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the size Ya of the first information signal, the size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:
(Ya+Yb)xe2x89xa7Rpxc2x7(Ra+Rb)xc2x7(Tab+Tba)/(Rpxe2x88x92Raxe2x88x92Rb) 
A fourth aspect of this invention provides an apparatus for reproducing information from a recording medium having first and second areas on which first and second information signals are recorded respectively. The apparatus comprises a head for reproducing the first and second information signals from the first and second areas of the recording medium and transmitting the reproduced first and second information signals on a time sharing basis and at a predetermined constant transfer rate Rp while moving between the first and second areas of the recording medium; and a buffer memory for receiving the first and second information signals from the head at the predetermined constant transfer rate Rp, for temporarily storing the first and second information signals, and for outputting the first and second information signals at first and second transfer rates Ra and Rb respectively, the first and second transfer rates Ra and Rb being lower than the predetermined constant transfer rate Rp, the buffer memory having a capacity Ym; wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the capacity Ym of the buffer memory, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:
Ym greater than {(Rpxe2x88x92Ra)xc2x7Ra+(Rpxe2x88x92Rb)xc2x7Rb}xc2x7(Tab+Tba)/(Rpxe2x88x92Raxe2x88x92Rb) 
A fifth aspect of this invention provides an apparatus for recording information on a recording medium having first and second areas. The apparatus comprises a buffer memory for receiving first and second information signals at first and second transfer rates Ra and Rb respectively, for temporarily storing the first and second information signals, and for outputting the first and second information signals at a predetermined constant transfer rate Rp higher than the first and second transfer rates Ra and Rb, the buffer memory having a capacity Ym; and a head for receiving the first and second information signals from the buffer memory, and for recording the first and second information signals on the first and second areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving between the first and second areas of the recording medium; wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the capacity Ym of the buffer memory, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:
Ym greater than {(Rpxe2x88x92Ra)xc2x7Ra+(Rpxe2x88x92Rb)xc2x7Rb}xc2x7(Tab+Tba)/(Rpxe2x88x92Raxe2x88x92Rb) 
A sixth aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having first and second areas, the first area being loaded with a first information signal. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate Rp; and a buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate Ra lower than the predetermined constant transfer rate Rp, the buffer memory having a capacity Ym; the buffer memory being for receiving a second information signal at a second transfer rate Rb lower than the predetermined constant transfer rate Rp, for temporarily storing the second information signal, and for outputting the second information signal at the predetermined constant transfer rate Rp; the head being for receiving the second information signal from the buffer memory, and for recording the second information signal on the second area of the recording medium at the predetermined constant transfer rate Rp; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the second information signal on the second area of the recording medium on a time sharing basis while moving between the first and second areas of the recording medium; and wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the capacity Ym of the buffer memory, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:
Ym greater than {(Rpxe2x88x92Ra)xc2x7Ra+(Rpxe2x88x92Rb)xc2x7Rb}xc2x7(Tab+Tba)/(Rpxe2x88x92Raxe2x88x92Rb) 
A seventh aspect of this invention is based on the first aspect thereof, and provides an apparatus further comprising means for partitioning the buffer memory into first and second areas in accordance with values of the first and second transfer rates Ra and Rb, wherein the first and second areas in the buffer memory are assigned to the first and second information signals respectively.
An eighth aspect of this invention is based on the first aspect thereof, and provides an apparatus further comprising means for partitioning the buffer memory into first and second areas in accordance with an operation mode, wherein the first and second areas in the buffer memory are assigned to the first and second information signals respectively.
A ninth aspect of this invention is based on the first aspect thereof, and provides an apparatus further comprising a first unit containing the head, and a second unit detachably connected with the first unit and containing the buffer memory.
A tenth aspect of this invention provides an apparatus comprising a head for reproducing an information signal from a recording medium and transmitting the reproduced information signal at a predetermined constant transfer rate; a buffer memory for receiving the information signal from the head at the predetermined constant transfer rate, for temporarily storing the information signal, and for outputting the information signal at a transfer rate lower than the predetermined constant transfer rate; a processor for receiving the information signal from the buffer memory and subjecting the information signal to a reproducing process; a first unit containing the head; and a second unit detachably connected with the first unit and containing the buffer memory and the processor.
An eleventh aspect of this invention provides an information-signal communication apparatus comprising the apparatus of the fist aspect of this invention and an interface connected with the buffer memory for communication with an external.
A twelfth aspect of this invention is based on the eleventh aspect thereof, and provides an information-signal communication apparatus further comprising a first unit containing the head, and a second unit detachably connected with the first unit and the interface and containing the buffer memory.
A thirteenth aspect of this invention provides an information-signal recording medium having first and second areas on which first and second information signals are recorded respectively, the first information signal having a size Ya, the second information signal having a size Yb, wherein the first and second information signals can be reproduced from the first and second areas and can be transmitted by a head on a time sharing basis and at a predetermined constant transfer rate Rp while the head moves between the first and second areas of the recording medium, wherein the first and second information signals outputted from the head can be received by a buffer memory at the predetermined constant transfer rate Rp and can be temporarily stored in the buffer memory before being outputted from the buffer memory at first and second transfer rates Ra and Rb respectively, the first and second transfer rates Ra and Rb being lower than the predetermined constant transfer rate Rp, wherein the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, the size Ya of the first information signal, the size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:
(Ya+Yb)xe2x89xa7Rpxc2x7(Ra+Rb)xc2x7(Tab+Tba)/(Rpxe2x88x92Raxe2x88x92Rb) 
A fourteenth aspect of this invention provides an apparatus for reproducing information from a recording medium having xe2x80x9cnxe2x80x9d areas on which xe2x80x9cnxe2x80x9d information signals are recorded respectively, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a head for reproducing the xe2x80x9cnxe2x80x9d information signals from the xe2x80x9cnxe2x80x9d areas of the recording medium and transmitting the reproduced xe2x80x9cnxe2x80x9d information signals on a time sharing basis and at a predetermined constant transfer rate Rp while moving among the xe2x80x9cnxe2x80x9d areas of the recording medium; and a buffer memory for receiving the xe2x80x9cnxe2x80x9d information signals from the head at the predetermined constant transfer rate Rp, for temporarily storing the xe2x80x9cnxe2x80x9d information signals, and for outputting the xe2x80x9cnxe2x80x9d information signals at transfer rates R1, R2, . . . , Rn respectively, the transfer rates R1, R2, . . . , Rn being lower than the predetermined constant transfer rate Rp; wherein the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, a sum xcexa3Yn of sizes of the xe2x80x9cnxe2x80x9d information signals, and a sum xcexa3Sn of seek times taken by the head to move from present ones to next ones of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ynxe2x89xa7Rpxc2x7xcexa3Rnxc2x7xcexa3Sn/(Rpxe2x88x92xcexa3Rn) 
A fifteenth aspect of this invention provides an apparatus for recording information on a recording medium having xe2x80x9cnxe2x80x9d areas, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or grater than 2. The apparatus comprises a buffer memory for receiving xe2x80x9cnxe2x80x9d information signals at transfer rates R1, R2, . . . , Rn respectively, for temporarily storing the xe2x80x9cnxe2x80x9d information signals, and for outputting the xe2x80x9cnxe2x80x9d information signals at a predetermined constant transfer rate Rp higher than the transfer rates R1, R2, . . . , Rn; and a head for receiving the xe2x80x9cnxe2x80x9d information signals from the buffer memory, and for recording the xe2x80x9cnxe2x80x9d information signals on the xe2x80x9cnxe2x80x9d areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving among the xe2x80x9cnxe2x80x9d areas of the recording medium; wherein the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, a sum xcexa3Yn of sizes of the xe2x80x9cnxe2x80x9d information signals, and a sum xcexa3Sn of seek times taken by the head to move from present ones to next ones of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ynxe2x89xa7Rpxc2x7xcexa3Rnxc2x7xcexa3Sn/(Rpxe2x88x92xcexa3Rn) 
A sixteenth aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having xe2x80x9cnxe2x80x9d areas, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2, wherein at least a first area among the xe2x80x9cnxe2x80x9d areas is loaded with a first information signal among xe2x80x9cnxe2x80x9d information signals. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate Rp; and a buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate R1 lower than the predetermined constant transfer rate Rp; the buffer memory being for receiving the xe2x80x9cnxe2x80x9d information signals except the first information signal at transfer rates R2, R3, . . . , Rn respectively, for temporarily storing the xe2x80x9cnxe2x80x9d information signals except the first information signal, and for outputting the xe2x80x9cnxe2x80x9d information signals except the first information signal at the predetermined constant transfer rate Rp, the transfer rates R2, R3, . . . , Rn being lower than the predetermined constant transfer rate Rp; the head being for receiving the xe2x80x9cnxe2x80x9d information signals except the first information signal from the buffer memory, and for recording the xe2x80x9cnxe2x80x9d information signals except the first information signal on the xe2x80x9cnxe2x80x9d areas of the recording medium except the first area at the predetermined constant transfer rate Rp; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the xe2x80x9cnxe2x80x9d information signals except the first information signal on the xe2x80x9cnxe2x80x9d areas of the recording medium except the first area on a time sharing basis while moving among the xe2x80x9cnxe2x80x9d areas of the recording medium; and wherein the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, a sum xcexa3Yn of sizes of the xe2x80x9cnxe2x80x9d information signals, and a sum xcexa3Sn of seek times taken by the head to move from present ones to next ones of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ynxe2x89xa7Rpxc2x7xcexa3Rnxc2x7xcexa3Sn/(Rpxe2x88x92xcexa3Rn) 
A seventeenth aspect of this invention provides an apparatus for reproducing information from a recording medium having xe2x80x9cnxe2x80x9d areas on which xe2x80x9cnxe2x80x9d information signals are recorded respectively, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a head for reproducing the xe2x80x9cnxe2x80x9d information signals from the xe2x80x9cnxe2x80x9d areas of the recording medium and transmitting the reproduced xe2x80x9cnxe2x80x9d information signals on a time sharing basis and at a predetermined constant transfer rate Rp while moving among the xe2x80x9cnxe2x80x9d areas of the recording medium; and a buffer memory for receiving the xe2x80x9cnxe2x80x9d information signals from the head at the predetermined constant transfer rate Rp, for temporarily storing the xe2x80x9cnxe2x80x9d information signals, and for outputting the xe2x80x9cnxe2x80x9d information signals at transfer rates R1, R2, . . . , Rn respectively, the transfer rates R1, R2, . . . , Rn being lower than the predetermined constant transfer rate Rp; wherein the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, a sum xcexa3Yn of sizes of the xe2x80x9cnxe2x80x9d information signals, and an allowable seek time S taken by the head to move from present one to next one of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ynxe2x89xa7Rpxc2x7xcexa3Rnxc2x7nxc2x7S/(Rpxe2x88x92xcexa3Rn) 
An eighteenth aspect of this invention provides an apparatus for recording information on a recording medium having xe2x80x9cnxe2x80x9d areas, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a buffer memory for receiving xe2x80x9cnxe2x80x9d information signals at transfer rates R1, R2, . . . , Rn respectively, for temporarily storing the xe2x80x9cnxe2x80x9d information signals, and for outputting the xe2x80x9cnxe2x80x9d information signals at a predetermined constant transfer rate Rp higher than the transfer rates R1, R2, . . . , Rn; and a head for receiving the xe2x80x9cnxe2x80x9d information signals from the buffer memory, and for recording the xe2x80x9cnxe2x80x9d information signals on the xe2x80x9cnxe2x80x9d areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving among the xe2x80x9cnxe2x80x9d areas of the recording medium; wherein the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, a sum xcexa3Yn of sizes of the xe2x80x9cnxe2x80x9d information signals, and an allowable seek time S taken by the head to move from present one to next one of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ynxe2x89xa7Rpxc2x7xcexa3Rnxc2x7nxc2x7S/(Rpxe2x88x92xcexa3Rn) 
A nineteenth aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having xe2x80x9cnxe2x80x9d areas, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2, wherein at least a first area among the xe2x80x9cnxe2x80x9d areas is loaded with a first information signal among xe2x80x9cnxe2x80x9d information signals. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate Rp; and a buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate R1 lower than the predetermined constant transfer rate Rp; the buffer memory being for receiving the xe2x80x9cnxe2x80x9d information signals except the first information signal at transfer rates R2, R3, . . . , Rn respectively, for temporarily storing the xe2x80x9cnxe2x80x9d information signals except the first information signal, and for outputting the xe2x80x9cnxe2x80x9d information signals except the first information signal at the predetermined constant transfer rate Rp, the transfer rates R2, R3, . . . , Rn being lower than the predetermined constant transfer rate Rp; the head being for receiving the xe2x80x9cnxe2x80x9d information signals except the first information signal from the buffer memory, and for recording the xe2x80x9cnxe2x80x9d information signals except the first information signal on the xe2x80x9cnxe2x80x9d areas of the recording medium except the first area at the predetermined constant transfer rate Rp; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the xe2x80x9cnxe2x80x9d information signals except the first information signal on the xe2x80x9cnxe2x80x9d areas of the recording medium except the first area on a time sharing basis while moving among the xe2x80x9cnxe2x80x9d areas of the recording medium; and wherein the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, a sum xcexa3Yn of sizes of the xe2x80x9cnxe2x80x9d information signals, and an allowable seek time S taken by the head to move from present one to next one of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ynxe2x89xa7Rpxc2x7xcexa3Rnxc2x7nxc2x7S/(Rpxe2x88x92xcexa3Rn) 
A twentieth aspect of this invention provides an apparatus for reproducing information from a recording medium having xe2x80x9cnxe2x80x9d areas on which xe2x80x9cnxe2x80x9d information signals are recorded respectively, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a head for reproducing the xe2x80x9cnxe2x80x9d information signals from the xe2x80x9cnxe2x80x9d areas of the recording medium and transmitting the reproduced xe2x80x9cnxe2x80x9d information signals on a time sharing basis and at a predetermined constant transfer rate Rp while moving among the xe2x80x9cnxe2x80x9d areas of the recording medium; and a buffer memory for receiving the xe2x80x9cnxe2x80x9d information signals from the head at the predetermined constant transfer rate Rp, for temporarily storing the xe2x80x9cnxe2x80x9d information signals, and for outputting the xe2x80x9cnxe2x80x9d information signals at transfer rates R1, R2, . . . , Rn respectively, the transfer rates R1, R2, . . . , Rn being lower than the predetermined constant transfer rate Rp, the buffer memory having a capacity Ym; wherein the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, the capacity Ym of the buffer memory, and a sum xcexa3Sn of seek times taken by the head to move from present ones to next ones of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ym greater than Rpxc2x7xcexa3Rnxc2x7xcexa3Sn/(Rpxe2x88x92xcexa3Rn) 
A twenty-first aspect of this invention provides an apparatus for recording information on a recording medium having xe2x80x9cnxe2x80x9d areas, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a buffer memory for receiving xe2x80x9cnxe2x80x9d information signals at transfer rates R1, R2, . . . , Rn respectively, for temporarily storing the xe2x80x9cnxe2x80x9d information signals, and for outputting the xe2x80x9cnxe2x80x9d information signals at a predetermined constant transfer rate Rp higher than the transfer rates R1, R2, . . . , Rn, the buffer memory having a capacity Ym; and a head for receiving the xe2x80x9cnxe2x80x9d information signals from the buffer memory, and for recording the xe2x80x9cnxe2x80x9d information signals on the xe2x80x9cnxe2x80x9d areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving among the xe2x80x9cnxe2x80x9d areas of the recording medium; wherein the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, the capacity Ym of the buffer memory, and a sum xcexa3Sn of seek times taken by the head to move from present ones to next ones of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ym greater than Rpxc2x7xcexa3Rnxc2x7xcexa3Sn/(Rpxe2x88x92xcexa3Rn) 
A twenty-second aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having xe2x80x9cnxe2x80x9d areas, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2, wherein at least a first area among the xe2x80x9cnxe2x80x9d areas is loaded with a first information signal among xe2x80x9cnxe2x80x9d information signals. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate Rp; and a buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate RI lower than the predetermined constant transfer rate Rp, the buffer memory having a capacity Ym; the buffer memory being for receiving the xe2x80x9cnxe2x80x9d information signals except the first information signal at transfer rates R2, R3, . . . , Rn respectively, for temporarily storing the xe2x80x9cnxe2x80x9d information signals except the first information signal, and for outputting the xe2x80x9cnxe2x80x9d information signals except the first information signal at the predetermined constant transfer rate Rp, the transfer rates R2, R3, . . . , Rn being lower than the predetermined constant transfer rate Rp; the head being for receiving the xe2x80x9cnxe2x80x9d information signals except the first information signal from the buffer memory, and for recording the xe2x80x9cnxe2x80x9d information signals except the first information signal on the xe2x80x9cnxe2x80x9d areas of the recording medium except the first area at the predetermined constant transfer rate Rp; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the xe2x80x9cnxe2x80x9d information signals except the first information signal on the xe2x80x9cnxe2x80x9d areas of the recording medium except the first area on a time sharing basis while moving among the xe2x80x9cnxe2x80x9d areas of the recording medium; and wherein the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, the capacity Ym of the buffer memory, and a sum xcexa3Sn of seek times taken by the head to move from present ones to next ones of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ym greater than Rpxc2x7xcexa3Rnxc2x7xcexa3Sn/(Rpxe2x88x92xcexa3Rn) 
A twenty-third aspect of this invention provides an apparatus for recording information on a recording medium having xe2x80x9cnxe2x80x9d areas, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a buffer memory for receiving xe2x80x9cnxe2x80x9d information signals at transfer rates R1, R2, . . . , Rn respectively, for temporarily storing the xe2x80x9cnxe2x80x9d information signals, and for outputting the xe2x80x9cnxe2x80x9d information signals at a predetermined constant transfer rate Rp higher than the transfer rates R1, R2, . . . , Rn; a head for receiving the xe2x80x9cnxe2x80x9d information signals from the buffer memory, and for recording the xe2x80x9cnxe2x80x9d information signals on the xe2x80x9cnxe2x80x9d areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving among the xe2x80x9cnxe2x80x9d areas of the recording medium; means for deciding whether or not parameters including the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, a sum xcexa3Yn of sizes of the xe2x80x9cnxe2x80x9d information signals, and a sum xcexa3Sn of seek times taken by the head to move from present ones to next ones of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ynxe2x89xa7Rpxc2x7xcexa3Rnxc2x7xcexa3Sn/(Rpxe2x88x92xcexa3Rn) 
means for, in cases where it is decided that the parameters are in the relation, permitting the head to record the xe2x80x9cnxe2x80x9d information signals on the xe2x80x9cnxe2x80x9d areas of the recording medium respectively; means for, in cases where it is decided that the parameters are not in the relation, selecting xe2x80x9cpxe2x80x9d information signals from among the xe2x80x9cnxe2x80x9d information signals, where xe2x80x9cpxe2x80x9d denotes a predetermined natural number smaller than xe2x80x9cnxe2x80x9d; means for deciding whether or not the parameters are in the relation regarding the xe2x80x9cpxe2x80x9d information signals; and means for, in cases where it is decided that the parameters are in the relation regarding the xe2x80x9cpxe2x80x9d information signals, permitting the head to record the xe2x80x9cpxe2x80x9d information signals on xe2x80x9cpxe2x80x9d areas of the recording medium respectively, the xe2x80x9cpxe2x80x9d areas being among the xe2x80x9cnxe2x80x9d areas of the recording medium.
A twenty-fourth aspect of this invention provides an apparatus for recording information on a recording medium having xe2x80x9cnxe2x80x9d areas, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2. The apparatus comprises a buffer memory for receiving xe2x80x9cnxe2x80x9d information signals at transfer rates R1, R2, . . . , Rn respectively, for temporarily storing the xe2x80x9cnxe2x80x9d information signals, and for outputting the xe2x80x9cnxe2x80x9d information signals at a predetermined constant transfer rate Rp higher than the transfer rates R1, R2, . . . , Rn; a head for receiving the xe2x80x9cnxe2x80x9d information signals from the buffer memory, and for recording the xe2x80x9cnxe2x80x9d information signals on the xe2x80x9cnxe2x80x9d areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate Rp while moving among the xe2x80x9cnxe2x80x9d areas of the recording medium; means for deciding whether or not parameters including the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, a sum xcexa3Yn of sizes of the xe2x80x9cnxe2x80x9d information signals, and a sum xcexa3Sn of seek times taken by the head to move from present ones to next ones of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ynxe2x89xa7Rpxc2x7xcexa3Rnxc2x7xcexa3Sn/(Rpxe2x88x92xcexa3Rn) 
means for, in cases where it is decided that the parameters are in the relation, permitting the head to record the xe2x80x9cnxe2x80x9d information signals on the xe2x80x9cnxe2x80x9d areas of the recording medium respectively; and means for, in cases where it is decided that the parameters are not in the relation, controlling the head to record the xe2x80x9cnxe2x80x9d information signals on a common area in the recording medium on a time sharing basis.
A twenty-fifth aspect of this invention is based on the twenty-fourth aspect thereof, and provides an apparatus further comprising means for rearranging the xe2x80x9cnxe2x80x9d information signals into xe2x80x9cnxe2x80x9d rearrangement-resultant information signals in the buffer memory, and for sequentially transmitting the xe2x80x9cnxe2x80x9d rearrangement-resultant information signals from the buffer memory to the head to sequentially record the xe2x80x9cnxe2x80x9d rearrangement-resultant signals.
A twenty-sixth aspect of this invention provides an apparatus for recording information on a recording medium. The apparatus comprises a buffer memory for receiving xe2x80x9cnxe2x80x9d information signals at transfer rates R1, R2, . . . , Rn respectively, for temporarily storing the xe2x80x9cnxe2x80x9d information signals, and for outputting the xe2x80x9cnxe2x80x9d information signals at a predetermined constant transfer rate Rp higher than the transfer rates R1, R2, . . . , Rn, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2; a head for receiving the xe2x80x9cnxe2x80x9d information signals from the buffer memory, and for recording the xe2x80x9cnxe2x80x9d information signals on the recording medium on a time sharing basis and at the predetermined constant transfer rate Rp; first means for causing the head to record the xe2x80x9cnxe2x80x9d information signals on at least two areas in the recording medium on a time sharing basis while moving the head among the areas in the recording medium under conditions where the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, a sum xcexa3Yn of sizes of the xe2x80x9cnxe2x80x9d information signals, and a sum xcexa3Sn of seek times taken by the head to move from present ones to next ones of the areas in the recording medium are in a relation as follows:
xcexa3Ynxe2x89xa7Rpxc2x7xcexa3Rnxc2x7xcexa3Sn/(Rpxe2x88x92xcexa3Rn) 
second means for causing the head to record the xe2x80x9cnxe2x80x9d information signal on a common area in the recording medium on a time sharing basis; and third means for selecting and enabling one of the first and second means.
A twenty-seventh aspect of this invention is based on the twenty-sixth aspect thereof, and provides an apparatus wherein the third means comprises means for selecting and enabling one of the first and second means in response to one of types of the xe2x80x9cnxe2x80x9d information signals, user""s requirement, apparatus specifications, a type of the recording medium, and a condition of a usable area in the recording medium.
A twenty-eighth aspect of this invention is based on the fourteenth aspect thereof, and provides an apparatus further comprising means for partitioning the buffer memory into xe2x80x9cnxe2x80x9d areas in accordance with values of the transfer rates R1, R2, . . . , Rn, wherein the xe2x80x9cnxe2x80x9d areas in the buffer memory are assigned to the xe2x80x9cnxe2x80x9d information signals respectively.
A twenty-ninth aspect of this invention is based on the fourteenth aspect thereof, and provides an apparatus further comprising means for partitioning the buffer memory into xe2x80x9cnxe2x80x9d areas in accordance with an operation mode, wherein the xe2x80x9cnxe2x80x9d areas in the buffer memory are assigned to the xe2x80x9cnxe2x80x9d information signals respectively.
A thirtieth aspect of this invention provides an information-signal communication apparatus comprising the apparatus of the fourteenth aspect of this invention and an interface connected with the buffer memory for communication with an external.
A thirty-first aspect of this invention provides an information-signal recording medium having xe2x80x9cnxe2x80x9d areas on which xe2x80x9cnxe2x80x9d information signals are recorded respectively, where xe2x80x9cnxe2x80x9d denotes a predetermined natural number equal to or greater than 2, wherein the xe2x80x9cnxe2x80x9d information signals can be reproduced from the xe2x80x9cnxe2x80x9d areas and can be transmitted by a head on a time sharing basis and at a predetermined constant transfer rate Rp while the head moves among the xe2x80x9cnxe2x80x9d areas of the recording medium, wherein the xe2x80x9cnxe2x80x9d information signals outputted from the head can be received by a buffer memory at the predetermined constant transfer rate Rp and can be temporarily stored in the buffer memory before being outputted from the buffer memory at transfer rates R1, R2, . . . , Rn respectively, the transfer rates R1, R2, . . . , Rn being lower than the predetermined constant transfer rate Rp, wherein the predetermined constant transfer rate Rp, a sum xcexa3Rn of the transfer rates R1, R2, . . . , Rn, a sum xcexa3Yn of sizes of the xe2x80x9cnxe2x80x9d information signals, and a sum xcexa3Sn of seek times taken by the head to move from present ones to next ones of the xe2x80x9cnxe2x80x9d areas of the recording medium are in a relation as follows:
xcexa3Ynxe2x89xa7Rpxc2x7xcexa3Rnxc2x7xcexa3Sn/(Rpxe2x88x92xcexa3Rn) 
A thirty-second aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having first and second areas and a management area, the management area storing management information representing addresses in the first and second areas. The apparatus comprises a first buffer memory for receiving a first information signal at a first transfer rate, for temporarily storing the first information signal, and for outputting the first information signal at a predetermined constant transfer rate higher than the first transfer rate; a second buffer memory for receiving a second information signal at a second transfer rate lower than the predetermined constant transfer rate, for temporarily storing the second information signal, and for outputting the second information signal at the predetermined constant transfer rate; a head for receiving the first and second information signals from the first and second buffer memories and recording the first and second information signals on the first and second areas of the recording medium respectively on a time sharing basis and at the predetermined constant transfer rate while moving between the first and second areas of the recording medium; means for controlling the head to reproduce the management information from the management area of the recording medium before the head records the first and second information signals; means for deriving the addresses from the reproduced management information; means for searching for unoccupied regions in the first and second areas of the recording medium in response to the derived addresses; and means for deciding whether or not the first and second information signals can be recorded on the unoccupied regions while recording continuities related to the first and second information signals are maintained.
A thirty-third aspect of this invention is based on the thirty-second aspect thereof, and provides an apparatus wherein the deciding means comprises means for deciding whether or not the first and second information signals can be recorded on the unoccupied regions while the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, a size Ya of the first information signal, a size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tha taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:
(Ya+Yb)xe2x89xa7Rpxc2x7(Ra+Rb)xc2x7(Tab+Tba)/(Rpxe2x88x92Raxe2x88x92Rb) 
A thirty-fourth aspect of this invention is based on the thirty-second aspect thereof, and provides an apparatus wherein the deciding means comprises means for deciding whether or not the first and second information signals can be recorded on the unoccupied regions while the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, a size Ya of the first information signal, a size Yb of the second information signal, and a maximum allowable seek time Tmax taken by the head to move on the recording medium are in a relation as follows:
(Ya+Yb)xe2x89xa72xc2x7Rpxc2x7(Ra+Rb)xc2x7Tmax/(Rpxe2x88x92Raxe2x88x92Rb) 
A thirty-fifth aspect of this invention provides an apparatus for recording and reproducing information on and from a recording medium having first and second areas and a management area, the first area being loaded with a first information signal, the management area storing management information representing addresses in the first and second areas. The apparatus comprises a head for reproducing the first information signal from the first area of the recording medium and transmitting the reproduced first information signal at a predetermined constant transfer rate; a first buffer memory for receiving the first information signal from the head at the predetermined constant transfer rate Rp, for temporarily storing the first information signal, and for outputting the first information signal at a first transfer rate lower than the predetermined constant transfer rate; a second buffer memory for receiving a second information signal at a second transfer rate lower than the predetermined constant transfer rate, for temporarily storing the second information signal, and for outputting the second information signal at the predetermined constant transfer rate; the head being for receiving the second information signal from the second buffer memory, and for recording the second information signal on the second area of the recording medium at the predetermined constant transfer rate; wherein the head implements reproduction of the first information signal from the first area of the recording medium and recording of the second information signal on the second area of the recording medium on a time sharing basis while moving between the first and second areas of the recording medium; means for controlling the head to reproduce the management information from the management area of the recording medium before the head records the second information signal; means for deriving the addresses from the reproduced management information; means for searching for an unoccupied region in the second area of the recording medium in response to the derived addresses; and means for deciding whether or not the second information signal can be recorded on the unoccupied region while a recording continuity related to the second information signal is maintained.
A thirty-sixth aspect of this invention is based on the thirty-fifth aspect thereof, and provides an apparatus wherein the deciding means comprises means for deciding whether or not the second information signal can be recorded on the unoccupied region while the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, a size Ya of the first information signal, a size Yb of the second information signal, a seek time Tab taken by the head to move from the first area to the second area of the recording medium, and a seek time Tba taken by the head to move from the second area to the first area of the recording medium are in a relation as follows:
(Ya+Yb)xe2x89xa7Rpxc2x7(Ra+Rb)xc2x7(Tab+Tba)/(Rpxe2x88x92Raxe2x88x92Rb) 
A thirty-seventh aspect of this invention is based on the thirty-fifth aspect thereof, and provides an apparatus wherein the deciding means comprises means for deciding whether or not the second information signal can be recorded on the unoccupied region while the predetermined constant transfer rate Rp, the first transfer rate Ra for the first information signal, the second transfer rate Rb for the second information signal, a size Ya of the first information signal, a size Yb of the second information signal, and a maximum allowable seek time Tmax taken by the head to move on the recording medium are in a relation as follows:
(Ya+Yb)xe2x89xa72xc2x7Rpxc2x7(Ra+Rb)xc2x7Tmax/(Rpxe2x88x92Raxe2x88x92Rb) 
A thirty-eighth aspect of this invention is based on the thirty-second aspect thereof, and provides an apparatus further comprising means for indicating a result of the deciding by the deciding means.
A thirty-ninth aspect of this invention is based on the thirty-second aspect thereof, and provides an apparatus further comprising means for calculating a first total capacity of the unoccupied regions, means for calculating a second total capacity of usable portions of the unoccupied regions, means for calculating an recording efficiency equal to a ratio between the first total capacity and the second total capacity, and means for indicating the calculated recording efficiency.
According to the basic aspects of this invention, the signal transfer rate related to the recording and reproduction of information on and from a recording medium is preferably fixed to the predetermined constant transfer rate Rp.
Generally, this invention can operate on a recording medium such as a DVD-ROM, a DVDxe2x88x92RW, a DVD-RAM, a DVD+RW, and an HDD magnetic disc.
A DVD-ROM or a DVDxe2x88x92RW is subjected to CLV (constant linear velocity) control by a disc drive. Thus, the signal transfer rate is fixed throughout the whole area of the DVD-ROM or the DVDxe2x88x92RW.
A DVD-RAM is divided into zones. The DVD-RAM is subjected to zone CLV by a disc drive. The signal transfer rate varies from zone to zone by only several percent. This invention is adaptable to such a slightly-varying signal transfer rate.
Regarding a DVD+RW or an HDD magnetic disc, the signal transfer rate sometimes depends on a disc radial position. This invention can be applied to a disc area in which the signal transfer rate varies by several percent to several tens of percent.
In these case, it is preferable to calculate the signal transfer rate (Rp) regarding a recording medium as a minimum signal transfer rate which occurs when recording or reproduction is performed.
In this invention, information is recorded on and reproduced from two or more areas of a recording medium. The two or more areas of the recording medium may be a common area. In this case, this invention is designed to operate in one of the following modes. During a first mode of operation, first data are reproduced from an area of a recording medium and a portion of the reproduced first data is changed to form second data, and the second data are recorded on the same area of the recording medium. During a second mode of operation, data are recorded on an area of a recording medium, and then the data are reproduced therefrom and the reproduced data are analyzed to verify whether the data have been correctly recorded on the area of the recording medium.